Publications (39)47.36 Total impact

[Show abstract][Hide abstract]ABSTRACT: Since the Gordius worm is a parasite of crickets and several arthropods, cases of humans infected with this worm have been rare and accidental. A Gordius worm was obtained from a three-year-old girl who consulted a local clinic in Gwangju, Kyunggi-do, Korea. She lived in a rural area, and had eaten an insect that looked like a cricket. She expelled the worm in vomitus 15 minutes later; in fact, she expelled two worms, but one was discarded. The worm had a grayish white color and an intact outer surface. It was 16 cm in length and 0.6 cm wide. The posterior end of the worm was spirally enrolled and furcated into two caudal lobes, which were nearly cylindrical but showed a somewhat concave medio- ventral surface. The cloacal aperture was round and situated anterior to the point of bifurcation of the lobes. The cloacal aperture was encircled by a dark ring, which was a little removed from the aperture. The crescent fold was reddish brown, and no hairs were noticed over the entire body surface. The worm had the morphological features of a male Gordius. Accidental human cases involving the Gordius worm are rare and this is the first such case in Korea.

[Show abstract][Hide abstract]ABSTRACT: The biology, chromosome number, and karyotype of a lung fluke, Paragonimus westermani (Kerbert, 1878) collected in Haenam, Haenam-gun Chollanam-do, Korea were analyzed. We compared the size of metacercariae from Haenam with those taken from a crayfish collected at Youngam, Youngam-gun, Chollanam-do, Korea. The mean length of P. westermani metacercariae from Haenam was 300.3 microm and that from Youngam was 362.0 microm. Adult worms were recovered from the lungs of experimentally infected dogs. The mean egg sizes obtained from adult flukes were 72.1 x 46.8 microm from Haenam and 93.5 x 54.2 microm from Youngam. Semisulcospira tegulata collected in the Youngam area were found to be infected with cercariae of P. westermani, one of the snail-borne human lung fluke trematodes in Korea. Of 4218 snails studied, 5 (0.12%) harbored P. westrermani larvae. This is the first report of S. tegulata serving as the initial intermediate host of P. westermani. The chromosome numbers of P. westermani from Haenam and Youngam were 2n = 22 and 3n = 33. The diploid type of P. westermani has not been previously reported in Korea.

[Show abstract][Hide abstract]ABSTRACT: An antigen-related gene was cloned from a cDNA expression library of Naegleria fowleri by immunoscreening with sera obtained from mice that were either immunized with an amoebic lysate or infected with trophozoites. The coding nucleotide sequence of the cloned gene consisted of 357 bases that were translated into 119 amino acids. This gene was designated as nfa1. The predicted amino acid sequence of Nfa1 protein has two potential glycosylation and three potential phosphorylation sites, and its predicted secondary structure consists of four helices and three corners. The deduced amino acid sequence of Nfa1 protein shares 43% identity with the myohemerythrin (myoHr) protein from a marine annelid, Nereis diversicolor, including 100% identity in conserved regions and iron-binding residues. A phylogenetic tree constructed from amino acid sequences placed the N. fowleri Nfa1 protein outside of a cluster of myoHr proteins from eight invertebrates. A purified recombinant protein that migrated as a 13.1 kDa species in SDS-PAGE was produced. This recombinant protein exhibited a strong immunoreactivity with infected, immune, and anti-Nfal sera. In addition, an anti-Nfa1 serum reacted with an amoeba lysate in immunoblotting analysis. The present nfal gene encoding the myoHr-like protein is the first myoHr gene cloned from protozoa, and the Nfal antigen may be useful in diagnostic studies

[Show abstract][Hide abstract]ABSTRACT: To determine whether pathogenic Acanthamoeba culbertsoni trophozoites and lysate can induce cytopathic changes in primary-culture microglial cells, morphological changes were observed by transmission electron microscopy (TEM). In addition, the secretion of two kinds of cytokines, tumor necrosis factor alpha (TNF-alpha) and interleukin-1beta (IL-1beta), from microglial cells was observed. Trophozoites of pathogenic A. culbertsoni made contact with microglial cells and produced digipodia. TEM revealed that microglial cells cocultured with amoebic trophozoites underwent a necrotic process, accompanied by lysis of the cell membrane. TEM of microglial cells cocultured with amoebic lysate showed that the membranes of the small cytoplasmic vacuoles as well as the cell membrane were lysed. The amounts of TNF-alpha secreted from microglial cells cocultured with A. culbertsoni trophozoites or lysate increased at 6 h of incubation. The amounts of IL-1beta secreted from microglial cells cocultured with A. culbertsoni trophozoites at 6 h of incubation was similar to those secreted from the control group, but the amounts decreased during cultivation with A. culbertsoni lysate. These results suggest that pathogenic A. culbertsoni induces the cytopathic effects in primary-culture rat microglial cells, with the effects characterized by necrosis of microglial cells and changes in levels of secretion of TNF-alpha and IL-1beta from microglial cells.

[Show abstract][Hide abstract]ABSTRACT: In order to observe the cytotoxicity of Acanthamoeba spp., which were isolated from contact lens containers as ethiological agents for the probable amoebic keratitis in Korea, the crystal violet staining method and LDH release assay were carried out. In the crystal violet staining method, among eight contact lens container isolates, isolate 3 (Acanthamoeba KA/LS5) showed 83.6% and 81.8% of cytotoxicity, and isolate 7 (Acanthamoeba KA/LS37) showed 28.2% and 25.1% of cytotoxicity, in 1 mg/ml and 0.5 mg/ml lysate treatments, respectively. Acanthamoeba culbertsoni and A. healyi showed 84.0% and 82.8% of cytotoxicity. Similar results were observed in A. castellanii and A. hatchetti which showed 83.6% and 75.5% of cytotoxicity. Acanthamoeba royreba and A. polyphaga showed 9.0% and 1.7% of cytotoxicity. In the LDH release assay, isolate 3 (20.4%) showed higher cytotoxicity than other isolates in 1 mg/ml lysate treatment. The results provide that at least isolate 3 has the cytotoxic effect against CHO cells and seems to be the pathogenic strain.

[Show abstract][Hide abstract]ABSTRACT: To determine whether trophozoites and lysates of pathogenic Acanthamoeba spp. induce apoptosis in primary-culture microglial cells, transmission electron microscopic (TEM) examinations, assessment of DNA fragmentation by agarose gel electrophoresis, and the TdT-mediated dUTP nick-end labeling assay were performed. When a trophozoite of pathogenic Acanthamoeba culbertsoni came in contact with a microglial cell, the digipodium was observed by TEM. Nuclear chromatin condensation was observed in 10% of microglial cells, while it was not revealed when they were cocultured with weakly pathogenic Acanthamoeba royreba trophozoites. DNA fragmentation in microglial cells cocultured with the A. culbertsoni lysate was detected by electrophoresis, showing DNA ladder formation, whereas it was hardly observed in microglial cells cocultured with A. royreba. DNA fragmentation of microglial cells was also confirmed by flow cytometry analysis. The fluorescence of TdT-stained apoptotic bodies became intensely visible with microglial cells cocultured with the A. culbertsoni lysate. In contrast, with microglial cells cocultured with the A. royreba lysate, only a background level of fluorescence of TdT-stained apoptotic bodies was detected. These results suggest that some rat microglial cells cocultured with pathogenic A. culbertsoni undergo cytopathic changes which show the characteristics of the apoptotic process, such as nuclear condensation and DNA fragmentation.

[Show abstract][Hide abstract]ABSTRACT: Human pulmonary dirofilariasis has been documented from many parts of the world, but not in Korea so far. We experienced a patient of pulmonary dirofilariasis who had visited a local clinic because of chest pain for 1 month. On chest radiograph, a coin lesion of 2 cm diameter and enlargement of the mediastinal lymph node were shown. An exploratory lung resection was done. Pathologically the lesion was a pulmonary dirofilariasis complicated with necrotic pneumonia, fibrosis, and infarction. At the center of the lesion, degenerated nematode sections with multilayered cuticle, thick musculature, and bilateral internal ridges on each side were found, which was identified to be Dirofilaria immitis. This is the first report of human pulmonary dirofilariasis in Korea.

[Show abstract][Hide abstract]ABSTRACT: In order to refer to the basic information regarding the identification of isolates obtained from a contact lens container in Korea, the isoelectric focusing gel electrophoresis was employed to compare the isoenzyme band patterns among Acanthamoeba spp. including eight isolates and the simple pairwise dissimilarity analysis was carried out. For an alkaline phosphate development, isolate 7 and Acanthamoeba polyphaga showed homologous band patterns, and isolates 1, 2, and 3 showed the same patterns. For lactate dehydrogenase, similar patterns were observed in isolates 2 and 3. Isolates 3 and 5 showed homologous band patterns for malate dehydrogenase and glucose phosphate isomerase. For hexokinase, isolates 4, 7, and A, hatchetti showed the same band patterns. In others, a considerable number of interstrain polymorphisms was observed in nine isoenzyme band patterns. In Acanthamoeba group II, genetic distances among isolates 1, 2, 3, 4, and 5 ranged from 0.104 to 0.200. In comparison to A. castellanii, A. hatchetti, and A. polyphaga, genetic distances of isolates 7 and 8 were 0.254 and 0.219, respectively. In Acanthamoeba group III, including A. culbertsoni, A. healyi, and A. royreba, isolate 6 had genetic distances which ranged from 0.314 to 0.336. Finally, when comparing to the six reference Acanthamoeba, it was possible to classify isolates 1, 2, 3, 4, and 5, as genetically close-related species and as independent species group. Furthermore, isolates 6, 7 and 8 were identified as independent species as well.

[Show abstract][Hide abstract]ABSTRACT: Identification of the genes responsible for the recovery of virulence in brain-passaged Acanthamoeba culbertsoni was attempted via mRNA differential display-polymerase chain reaction (mRNA DD-PCR) analysis. In order to identify the regulatory changes in transcription of the virulence related genes by the brain passages, mRNA DD-PCR was performed which enabled the display of differentially transcribed mRNAs after the brain passages. Through mRNA DD-PCR analysis. 96 brain-passaged amoeba specific amplicons were observed and were screened to identify the amplicons that failed to amplify in the non-brain-passaged amoeba mRNAs. Out of the 96 brain-passaged amoeba specific amplicons, 12 turned out to be amplified only from the brain-passaged amoeba mRNAs by DNA slot blot hybridization. The clone, A289C, amplified with an arbitrary primer of UBC #289 and the oligo dT11-C primer, revealed the highest homology (49.8%) to the amino acid sequences of UPD-galactose lipid transferase of Erwinia amylovora, which is known to act as an important virulence factor. The deduced amino acid sequences of an insert DNA in clone A289C were also revealed to be similar to cpsD, which is the essential gene for the expression of type III capsule in group B streptococcus. Upregulated expression of clone A289C was verified by RNA slot blot hybridization. Similar hydrophobicity values were also observed between A289C (at residues 47-66) and the AmsG gene of E. amylovora (at residues 286-305: transmembrane domains). This result suggested that the insert of clone A289C might play the same function as galactosyl transferase controlled by the AmsG gene in E. amylovora.

[Show abstract][Hide abstract]ABSTRACT: To determine the pathogenicity of Acanthamoeba spp. isolated in Korea and to develop a isoenzymatic maker, the mortality rate of infected mice, in vitro cytotoxicity against target cells and isoenzyme band patterns were observed. Five isolates of Acanthamoeba spp. (YM-2, YM-3, YM-4, YM-5, and YM-7) were used in this study as well as three reference Acanthamoeba spp. (A. culbertsoni, A. hatchetti, and A. royreba). According to the mortality rate of infected mice, Korean isolates could be categorized into three groups high virulent (YM-4), low virulent (YM-2, YM-5, YM-7) and the nonpathogenic group (YM-3). In addition, the virulence of Acanthamoeba spp. was enhanced by brain passage in mice. In the cytotoxicity assay against chinese hamster ovary cells, especially, the cytotoxicity of brain-passaged amoebae was relatively higher than the long-term cultivated ones. The zymodeme patterns of glucose-6-phosphate dehydrogenase (G6PD), malate dehydrogenase (MDH), hexokinase (HK), glutamate oxaloacetate transaminase (GOT) and malic enzyme (ME) of Acanthamoeba spp. were different among each isolate, and also between long-term cultured amoebae and brain passaged ones. In spite of the polymorphic zymodemes, a slow band of G6PD and HK, and an intermediate band of MDH were only observed in pathogenic Acanthamoeba spp., which should be used as isoenzymatic makers.

[Show abstract][Hide abstract]ABSTRACT: The first case was 7-month-old immunodeficiency girl in whom the diagnosis of Acanthamoeba pneumonia was established by culture of a bronchial washing. The patient had been ill for a month when she was admitted due to neonatal thrombocytopenia with respiratory difficulty and treated with gammaglobulin and steroid. Her chest X-ray showed diffuse alveolar consolidation on the left lung with interstitial hazziness and a partial sign of hyperinflation on the right lung. Laboratory tests showed that the Candida antigen was negative and Pneumocystis carinii was not detected. Mycoplasma antigen was negative. All the immunoglobulin levels (IgG, IgA, IgM) were below the normal range. Five days later the patient expired. The second case was an immunosuppressed 7-year-old boy in whom Acanthamoeba trophozoites were found in the skin biopsy, followed by meningitis leading to death. About five days after a laceration on the region of the left eyebrow, a painful bean-sized nodule developed at the suture site and it was treated with antibiotics and corticosteroid. The skin biopsy showed severe inflammatory cell infiltration. Trophozoites were scattered near the blood vessels throughout the inflammatory zone. From one weak prior to admission, the patient had suffered from vomiting, indigestion and mild fever. Skin nodules with tenderness appeared all over his body surface. Examination of cerebrospinal fluid showed clear, Gram stain was negative, bacterial culture negative, India ink preparation negative, and organism on wet smear negative. On admission day 10, focal seizure of the left extremity occurred. Brain CT revealed calcific density on the left parietal lobe area and hypodensity on the left basal ganglia. He became comatous and died immediately after discharge. Until now in Korea, two cases that are described in this paper, one Acanthamoeba meningoencephalitis case and seven Acanthamoeba keratitis cases including two unreported keratitis cases that are reported in this paper have been presented.

[Show abstract][Hide abstract]ABSTRACT: The prevalence of Loa loa infections in non-endemic areas such as Korea is very low, even though it is quite common in the endemic regions of West and Central Africa. We describe a patient who presented with temporary localized edema (classical Calabar swellings) after travelling to Cameroon and in whom the diagnosis of loiasis was made by ELISA. This is the second reported case of loiasis in Korea. As international travel is becoming more frequent, Loa loa infection should be considered in the differential diagnosis for patients with eosinophilia and Calabar swellings in Korea.

[Show abstract][Hide abstract]ABSTRACT: The differential display reverse transcription polymerase chain reaction (DDRT-PCR) analysis was performed to identify the pathogenic strain specific amplicons. mRNAs were purified from the trophozoites of the pathogenic strain YS-27 and the non-pathogenic strain S 16, respectively. Three kinds of first stranded cDNAs were reverse transcribed from the mRNAs by one base anchored oligo-dT11M (M: A, C, or G) primers. Each cDNA template was used for DDRT-PCR analysis. A total of 144 pathogenic strain specific amplicons was observed in DDRT-PCR analysis using primer combinations of the 11 arbitrary primers and the 3 one base anchored oligo-dT11M primers. Of these, 31 amplicons were verified as the amplicons amplified only from the mRNAs of the pathogenic strain by DNA slot blot hybridization. Further characterization of the 31 pathogenic strain specific amplicons by DNA slot blot hybridization analysis using biotin labeled probes of the PCR amplified DNA of cysteine proteinase genes revealed that 21 of them were amplified from the mRNAs of the cysteine proteinase genes. Four randomly selected amplicons out of the rest 10 amplicons were used for screening of cDNA library followed by immunoscreening and all of them were turned out to be amplified from the mRNA.

[Show abstract][Hide abstract]ABSTRACT: Acanthamoeba sp. YM-4 is similar to A. culbertsoni based upon morphological characteristics of trophozoites and cysts. However, based on other characteristics, pathogenicity to mice, in vitro cytotoxicity and isoenzyme patterns. Acanthamoeba sp. YM-4 was quite different from A. culbertsoni. Restriction fragment length polymorphism (RFLP) analysis of mtDNA is useful in the classification of members belonging to the genus Acanthamoeba. Therefore, in this study, RFLP analysis of Acanthamoeba mtDNAs was accomplished using five restriction enzymes: HaeIII, HindIII, ClaI, PvuII and SalI. Each restriction enzyme produced approximately 3-15 fragments (range: from 0.6 kbp to 34.4 kbp). The mtDNA genome size, calculated by the summation of restriction fragments, averaged 46.4 kbp in Acanthamoeba sp. YM-4, 48.3 kbp in A. culbertsoni and 48.8 kbp in A. polyphaga, respectively. Digested mtDNA fragments of Acanthamoeba sp. YM-4 contained nine and seven same size fragments, respectively, from a total of 67 and 69 fragments observed in A. culbertsoni and A. polyphaga. An estimate of the genetic divergence was 10.1% between Acanthamoeba sp. YM-4 and A. culbertsoni, and 9.9% between Acanthamoeba sp. YM-4 and A. polyphaga.

[Show abstract][Hide abstract]ABSTRACT: Genetic status of Acanthamoeba spp. were tested on the basis of random amplified polymorphic DNA (RAPD) marker analysis. Four previously established Acanthamoeba species, 4 Korean isolates of Acanthamoeba sp., and one American isolate of Acanthamoeba sp. were analyzed by RAPD-PCR using an arbitrary decamer primers. Amplification products were fractionated by agarose gel electrophoresis and stained by ethidium bromide. Eighteen primers produced DNA amplification profiles revealing clear differences among 4 species. Nine of them also produced DNA amplification profiles which included some isolate-specific amplification products. On the basis of amplified fragments by 18 primers, the pairwise similarity indices between A. culbertsoni and other species (i.e., A. hatchetti, A. triangularis, A. polyphaga) were 0.300, 0.308, and 0.313, respectively. Similarity index between A. hatchetti and A. triangularis was 0.833. The mean similarity index among the 3 Korean isolates (YM-2, -3, -4) was 0.959 and 0.832 among them and 2 other species (A. hatchetti and A. triangularis). The mean similarity index among YM-5 and other Korean isolates (YM-2, -3, -4) was 0.237. However, the similarity index between YM-5 and A. culbertsoni was 0.857, which suggests that YM-5 is genetically more similar to A. culbertsoni than other Korean isolates. Phenogram reconstructed by UPGMA method revealed that there are two groups: one group consists of A. hatchetti, A. triangularis, and 3 Korean isolates (YM-2, -3, -4), and the other group consists of A. culbertsoni, A. polyphaga, HOV, and YM-5.

[Show abstract][Hide abstract]ABSTRACT: Human anisakiasis may occur after ingestion of raw marine fish infected with nematode larvae of Anisakidae. Anisakiasis caused by the migration of the larva into the wall of stomach, small intestine and other portion has been reported in Korea. This prospective study was made of all cases referred to parasitological laboratory in Cheju-do between June 1989 and June 1992. Gastric anisakiasis was confirmed if larvae invading the gastric wall were observed by gastrofiberscopy. One hundred and seven cases were diagnosed, most of which were in 30-49 years old. Most of the patients complained acute epigastric pain with history of eating raw marine fish. This symptom usually occurred about 12 hours to 1 day after ingestion of infected marine fish. Edema, erosion or ulcer of the mucosa and hemorrhage from the gastric wall were observed in the involved areas. Ninety larvae removed from the stomach were identified; the larva of Anisakis simplex was the most prevalent species, and the larva of Pseudoterranova decipiens was also detected. The important species of marine fish from which the patients became infected was demonstrated as yellow corvina, sea eel, ling, cuttle fish, yellowtail and others. Five species of marine fish as a possible source of infection were examined, and Anisakis simplex larvae and Pseudoterranova decipiens larvae were collected from the mackerel and rock cod. This study demonstrates that anisakiasis is recognized as a public health problem in Korea.

[Show abstract][Hide abstract]ABSTRACT: To clarify the correlation of the proteinase activity with pathogenicity of Clonorchis sinensis, the proteinase activity either in excretory-secretory products (ESP) or in crude extracts of adult C. sinensis was examined. Substrate gel electrophoresis of the ESP and crude extracts revealed four distinct enzyme bands, which were differently inhibited by the specific proteinase inhibitors. The proteinase of the ESP with molecular mass of 24 kDa, was purified 23-fold with 14.5% yield by spectra gel ACA 44 gel filtration. It exhibited optimal pH at 7.5 in sodium phosphate (0.1 M). Its activity was inhibited specifically by N-ethylmaleimide (NEM) and antipain whereas potentiated 1.9 folds in the presence of 5 mM dithiothreitol (DTT). Cytotoxicity of the proteinase increased in a dose-dependent manner up to 120 micrograms/ml while reduced by NEM and antipain, indicating that cysteine proteinase was responsible for the cytotoxicity. This result shows that the 24 kDa cysteine proteinase is deeply correlated with the pathogenicity of C. sinensis infection.

[Show abstract][Hide abstract]ABSTRACT: The role of macrophages was observed in intranasally infected C3H/HeJ mice with trophozoites (3 x 10(5)) of Acanthamoeba culbertsoni which was a kind of free-living amoebae inducing meningoencephalitis in human and experimental animals. The mortality was 60% in the group of intraperitoneally injected mice with silica (0.5 mg/0.5 ml). It was much higher than that of 10% in the group of amoeba infected mice without silica administration. The phagocytic index of peritoneal macrophages co-cultured with Toxoplasma gondii was estimated daily. In contrast to the control and amoeba infected group which didn't show significant fluctuation of the phagocytic indices, the silica administrated group revealed under 3% until day 3, and gradual increase up to 24.7% in day 5 which was same level of amoeba infected group without silica administration. The level of interleukin-1b (IL-1b) measured by ELISA was the highest in the amoeba infected group without silica injection and the lowest in the amoeba infected group with silica administration. In the test of the amoebicidal activity of mice peritoneal macrophages in vitro, silica administration revealed reducing effect on amoebicidal activity of macrophages. In conclusion, macrophages were proven to play a significant role in defense mechanism against the development of experimentally induced Acanthamoeba meningoencephalitis.